A Carrier Aggregation (CA) technology is introduced in a Long Term Evolution-Advanced (LTE-A) system. That is, multiple Component Carriers (CC) are scheduled for one UE to fulfill a higher peak rate and service requirements.
In a system not based on the CA technology, resources of only one carrier can be scheduled by a piece of Physical Downlink Control Channel (PDCCH) signaling. In a system based on the CA technology, if a UE aggregates multiple carriers to transmit data, the UE requires multiple pieces of corresponding PDCCH signaling.
In an LTE-A system, resources can be scheduled in two modes. One mode is Same-CC Scheduling (SCS), which means that the PDCCH signaling on a carrier may be used to schedule only resources of this carrier and the uplink carrier corresponding to this carrier; the other mode is Cross-CC Scheduling (CCS), which means that the PDCCH signaling on a carrier may be used to schedule the resources of this carrier or other carriers. In CCS mode, a Carrier Indicator Field (CIF) needs to be added to UE-specific PDCCH signaling to indicate resources of which carrier are currently scheduled by the PDCCH signaling. Specially, no CIF is added to PDCCH signaling shared by multiple UEs so that the UEs in an LTE-A system and the UEs in an LTE system can coexist.
The base station sends semi-static Radio Resource Control (RRC) signaling to the UE, indicating whether the resource scheduling mode currently applied by the UE is CCS or SCS. When the UE uses the SCS mode to schedule resources in the RRC-idle state or the RRC-connected state, the PDCCH signaling includes no CIF. When the UE uses the CCS mode to schedule resources in the connected state, the PDCCH signaling includes a CIF. After the base station sends the semi-static RRC signaling to the UE, if the UE receives the semi-static RRC signaling, the UE detects and parses the PDCCH signaling according to the resource scheduling mode indicated in the semi-static RRC signaling. However, after the base station sends the semi-static RRC signaling, the base station is not sure whether the UE has received the semi-static RRC signaling correctly until the base station receives RRC Connection Reconfiguration Complete signaling (RRC Connection Reconfiguration Complete signaling) returned by the UE, and the scheduling on the base station is uncertain in the period from sending the semi-static RRC signaling to receiving the RRC Connection Reconfiguration Complete signaling.
The following problems exist in the prior art. The scheduling on the base station is uncertain in the period from sending the semi-static RRC signaling to receiving the RRC Connection Reconfiguration Complete signaling returned by the UE, which causes the UE to parse the signaling incorrectly.